Questions tagged [voip]

For questions about Voice over Internet Protocol (VoIP) which encompasses various technologies (methods, functions, and encapsulations) for encoding and delivering audio on a network using IP.

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10
votes
2answers
4k views

How can I disable SIP on IOS 12.x

How would I disable SIP on an Cisco router running IOS 12.x?
10
votes
1answer
37k views

How can I reasonably verify my QoS configuration is working?

Context I've deployed a standard QoS config to a customer site running a Cisco 891 router with IOS 15.1(4)M4. The WAN link is a single ADSL2+ link (24/1Mbps) connected to FE8. I've previously tested ...
8
votes
2answers
13k views

Difference between LLDP and LLDP-MED

What is the difference between LLDP and LLDP-MED? Is LLDP-MED an add-on to LLDP or something completely different?
8
votes
2answers
983 views

Troubleshooting One Way Audio

Quick question for the VoIP gurus. A while back I learned a trick where if I received a call on a VoIP phone, but after answering I couldn't hear anything, I would ask the person to press a number on ...
8
votes
1answer
380 views

Cisco callmanager SIP features

I am a programmer working in a software for the sales dept. I would like to know if a feature I want to implement is possible or not. The user has an application where he can see information about a ...
8
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4answers
558 views

QoS on a dedicated VOIP network

Is there any point in enabling QoS on a dedicated VOIP network that only has VOIP traffic?
7
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1answer
640 views

Overview of following cisco 2800 config

Here is the config of one of our routers. Can any one give an overview? I believe its for VOIP. We are going to replace this router with a non Cisco firewall, will there be any issue for VOIP in the ...
7
votes
5answers
13k views

Connect a POE VoIP phone to a non-POE Switch

I'm working on a project where I need to make a network for all PCs in the site. I need about 8 Ethernet sockets in each office of the site. I found that there's already two Ethernet sockets in each ...
6
votes
3answers
2k views

Is QoS an issue for VOIP calls over the Internet? If not, why not?

I'm trying to decide whether I should buy SIP trunks from my ISP or a 3rd-party. As I understand it, it's important to maintain QoS on an internal network (i.e. prioritize VOIP traffic). Is this not ...
6
votes
3answers
24k views

CUCM 10.5 - Reset Admin name & password

I need to reset my CUCM Admin password and name. On previous versions of Cisco Call Manager, I had to log in to CLI and run these commands : utils reset_ui_administrator_name utils ...
6
votes
2answers
3k views

Cisco IP Phone 7941 Never Asks for TFTP files?

I've been reading and googling for the past week trying to wrap my head around the Cisco IP Phone TFTP upgrade process. The effort has been to try and make a Cisco 7941G work with Asterisk. This ...
5
votes
1answer
15k views

Converting PCAP to WAV

How would I go about converting a RTP stream from a pcap file to wav format with a command-line tool such as sox?
5
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3answers
10k views

How is it possible to run VoIP on CAT3. Do you not need CAT5 for the voice data?

So I never knew this till today but I thought you needed CAT5 for VoIP but this business is running VoIP on CAT3. Don't you need the extra wires for the voice, data and power?
5
votes
2answers
2k views

Whats the difference between VOICE VLAN and ACCESS VLAN

Can someone please tell me the difference in Layman's termsfor these 2 configurations? interface FastEthernet0/1 description PHONES switchport mode access **switchport voice vlan 51** spanning-...
5
votes
2answers
8k views

Do i need to configure VLANS on my router/firewall or just the switch?

I finally took time to map my entire shitty network to understand exactly what the guy before me did, and i must admit i'm a little bit surprised even if i'm not a network expert... Just take a look ...
5
votes
1answer
504 views

Downstream QoS Feasibility

I work for a VoIP provider, and one of the biggest hassles I deal with is downstream traffic management. Our flagship product is QoS-enabled bonded T1 or SHDSL bundles configured to support our own ...
5
votes
2answers
5k views

Can't configure the Cisco CP-8851 IP Phone

I do not have a cisco contract or license, but I did order the Cisco CP-8851 IP Phone from Amazon, and was hoping that I could configure it to work with my VoIP SIP PBX. But I can't seem to log into ...
5
votes
1answer
290 views

VoIP QoS over DIA/L3VPN physical circuit

This Q. is really confirmation to what I already suspect. On a single physical interface with a carrier that uses two dot1q logical sub interfaces to handle DIA and L3VPN, I suspect any usage of DIA ...
4
votes
2answers
711 views

VLAN Tags Being Different for a VoIP Phone vs. the Host Daisy-Chained to it?

I've recently began working for a VoIP Provider and I am constantly seeing VoIP Phones pulling different VLANs than the Host that is connected to it i.e. daisy-chained. When I've tried to look more ...
4
votes
2answers
5k views

How do I tag traffic with a DSCP value on an ASA?

I have a SIP Server that does not put a DSCP code on it's traffic. This server is behind an ASA, and I want to prioritize its traffic passing through an ASA from the private to public network. I am ...
4
votes
1answer
248 views

What Is Session Border Controller [closed]

What is Session Border Controller(SBC). And What is the Advantages of SBC. How Does It Works?
4
votes
1answer
356 views

Is TCP slow start supposed to be enabled for VoIP SIP?

TCP slow start mechanism generally is pretty useful in most cases. But it is not so good and reasonable for short-lived TCP connections. Hence the question: Should TCP slow start be used with SIP-over-...
4
votes
2answers
3k views

Access Cisco Call Manager Express on 2811 Router

I'm trying to gain access to my business' Cisco 2811. I did the standard password reset following these procedures: http://www.cisco.com/en/US/products/hw/routers/ps259/...
4
votes
1answer
659 views

Can I Use Different Versions of CME and CUE

I am running CME 8.6 on a Cisco 2811. I would like to install NM-CUE and run CUE 7 with this. It this possible, even with a version mismatch?
4
votes
1answer
1k views

Call incoming from PSTN does not forward to cellphone number

We have a Cisco 2921 connected to an T1 ISDN PRI with Call Manager Express. We are using CP8861 SIP phones. Everything works fine, calling in and out. To better illustrate the problem here's an ...
4
votes
2answers
401 views

VLANs isolating networks (VoIP/Wi-Fi)

I have to set up our network in our new office. I'm no networking expert (developer), but I need some input and advice here for some things I wonder about. I have purchased the following: 2 x Cisco ...
4
votes
1answer
9k views

UDP Port Forwarding Range

We just purchased a cisco 3825 router running IOS 15.1. The slice of the topology in question is as follows: RTP (8000-20000) RTP (8000-20000) 192.168.2.1 <-------------->...
4
votes
2answers
1k views

IP Phones causing printing issue

Background We have Mitel IP phones. The phones use dhcp option 125 to get configuration information, and this tells them to use 802.11q tags for vlan id #5, with address range 192.168.16.0/24. Our ...
3
votes
3answers
471 views

What is the exact engineering involved behind creating a SIP trunk for any customer?

When a company is setting up a PBX and wants to use a SIP trunk, why does it have to buy it? Is there no way to provide itself with one on its own?
3
votes
1answer
287 views

Why is it necessary to pay for VOIP calls to phones?

I'd like to start by apologizing for not doing a thorough research on this subject, but after talking to a work mate VOIP came up. I know very roughly how it works (most basic knowledge you can ...
3
votes
3answers
949 views

LAN QoS for VoIP

Is LAN QoS required for VoIP applications? We have basic network infrastructure: PC (Softphone) -GigEth-> [Switch] -GigEth-> [Router/Firewall] -> Internet (100 Mbps) -> [ITSP] Voice ...
3
votes
1answer
399 views

VLAN VoIP and LAN configuration over multiple switches

Some background: I currently have: Switch A Main 48 port 1Gbps (DLink) Switch B 10Gbps Backbackbone (DLink) Switch C 24 port 1Gbps (DLink) Telephone Switch 1-24 port phone switch connected to a ...
3
votes
2answers
153 views

what is a data only mode card

I have a router (cisco 1841 modular router) and in the router's guide. They guide says that the c1841 is a data-only mode, even the VWIC cards is data only. I want to add a Polycom group series 500 ...
3
votes
1answer
131 views

catalyst 6509 using fxs card to convert analog to sip for an external pbx?

I am looking in to getting a 6509 with supervisor 2 module. I noticed that there was a fxs card avaiable and started to wonder if you had to use the unified software on a pc or if it would be ...
3
votes
3answers
376 views

Understanding of NAT and VoIP [closed]

I need some help to better understand how networks work, ports, and communication. Suppose we have this situation: We have on the left a corporate network (let's call it "A") which has a DMZ with a ...
3
votes
2answers
87 views

Which header is added to the voice data payload in Layer-2 when we use an IPsec VPN?

According to this link, Planning and Design, an encrypted IPsec voice data packet contains: IPsec header, ESP header, GRE IP header, IP header, UDP header, RTP header. Which header is added in Layer-...
3
votes
2answers
1k views

rtp connection with nat

Consider server S with some public ip and client C behind NAT N. Now C sends some messages on a UDP channel to S. Client C declares the port to which S should connect the RTP stream. As you might ...
3
votes
1answer
2k views

Outgoing call routing issue Avaya IP Office PBX

I have an Avaya IP Office PBX phone system. There is a T1 coming in for the trunk. There were 6 numbers associated tot he trunk. 4 of the numbers were taken off by Telco provider and converted to ...
3
votes
2answers
1k views

VoIP switch setup trouble

I have a brocade icx 6450 with the following config. The pc's are connected directly to the phones. I have port 1/1/48 going into another switch which is has the dhcp server for the data network ...
3
votes
1answer
86 views

How can I see if this line is an isdn30 line?

I got an port here from somewhere, and I'm guessing its an isdn30 line but I'm not sure. How can I check if its indeed an isdn30 line? I can plug my laptop in with an utp-cable but is there a program ...
3
votes
1answer
220 views

dmz and ip-phone on medium network

Hi I'm trying to sketch a computer network. The network include about 50 computers for employees, 20 computers for tech office, a few network printers, a wifi area and every employee has an ipPhone. ...
3
votes
1answer
283 views

VOIP timeout behind Cisco ASA after Duplicate ACK and Retransmissions

We have a RingCentral Polycom VVX series VOIP phone behind a Cisco ASA 5506 that will provision, work for about five minutes, go off-line for 20 minutes then reconnect and continue to work unless ...
3
votes
1answer
1k views

EX3300: Voice VLAN stopped working after upgrade to 15.1R6.7

We have 50+ Juniper EX3300 switches with access points configured to work with dot1x and voice vlan. We also have a variety of Yealink T23G, T42G, T26G and T48G phones that worked perfectly in our ...
3
votes
1answer
4k views

Cisco ASA SIP/RTP inspection question

I have following scenario: [VoIP phone]--------[ASA 5550]----------[SIP Server] VoIP phone: 10.0.0.10 SIP server: Public Address Question: In above scenario do i need to specify or open RTP ...
3
votes
1answer
541 views

Call is disconnected after huntstopped to another phone

We've been having an issue at the office with our Cisco CME. Here's the situation. Phone A (outside line) dials into the main line and after ~three rings the call is huntstopped to four other phones. ...
3
votes
1answer
615 views

Realtime Transfer Protocol (RTP) belongs to which layer of OSI?

Real-time Transfer Protocol (RTP) belongs to which layer of OSI? Various people said various things from transport-layer to application-layer.
3
votes
0answers
423 views

Cisco phone display name change

I am trying to change name on cisco ip phone 7942. I changed the name in directory number configuration and in phone configuration of phone on CUCM. I did reset of phone too. But still showing the old ...
3
votes
0answers
70 views

Configure C1861 for SIP to FXS port [closed]

I found a C1861 ISR router and I would like to play with it a learn some telephony. I signed up for a VOIP service so I have SIP credentials. Is there a simple walkthrough anywhere to set up the SIP ...
3
votes
0answers
1k views

Cisco 871, NAT, port formwarding and VOIP configuration - phone speaker buzz

I'm new to all Cisco stuff and I need to configure nettalk VOIP. I have Cisco 871 device with two ISP - one via PPP (public IP 666.666.666.666) and one via eth (public IP 999.999.999.999). Main ISP ...
2
votes
2answers
52 views

Cisco 3750 - configure to mimic multi location scenario

Good morning. For starters, I am less than a noob with cisco products. I can access, so basic trunking for our nec phone systems, etc. I have a 3750 that I'd like to configure to mimic a multi ...